When you change the chmod settings to 777 ensure you have the option selected to recursively apply that to all files and sub directories also. internal_directory and data and all their contents should be 777.

That being said, this is highly unlikely to be the cause.

The reason nothing is logged in the Server Error log is because this is happening at the web server before XenForo code is executing. Unfortunately your host has fobbed you off.

This is a 500 Internal Server Error. More details will be logged in the web server's logs. If you do not have access to these, then only your host can look at them and advise you what the errors are.

# If you are having problems with the rewrite rules, remove the "#" from the # line that begins "RewriteBase" below. You will also have to change the path # of the rewrite to reflect the path to your XenForo installation. #RewriteBase /xenforo

# This line may be needed to enable WebDAV editing with PHP as a CGI. #RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]

My host provider add this ones, becouse i have problems with 500 server error when try install plugins, i dont know what is change it but i got this ones from yesterday

PHP:

# Mod_security can interfere with uploading of content such as attachments. If you# cannot attach files, remove the "#" from the lines below.#<IfModule mod_security.c># SecFilterEngine Off# SecFilterScanPOST Off#</IfModule>

# If you are having problems with the rewrite rules, remove the "#" from the # line that begins "RewriteBase" below. You will also have to change the path # of the rewrite to reflect the path to your XenForo installation. #RewriteBase /xenforo

# This line may be needed to enable WebDAV editing with PHP as a CGI. #RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]

On some folders of you they are some .htaccess files , they can cause the problem. Please inform us when you get info about this. We will get you back on the other server you have the problem with news.

so my question its i delete htacces from public_html and leave only ones with text, so becouse i dont use full friendly URLs, it is any other htaccess files inside folders.